1. Field of the Invention
The invention relates generally to the fields of cargo screening, non-intrusive inspection (NII), non-destructive testing (NDT), and, more particularly, to systems and methods for calibrating such devices.
2. Description of the Related Art
Most currently available normalization filters for use with high energy imaging systems are referred to as “step wedge” devices. A step wedge is a single block of material which is cut into steps. Each step is a different thickness that may be placed into the radiation beam. To have many thicknesses one must have many steps. Since each step is in series the wedge is driven with a positioning system which can place each step in the beam. This requires a motion control capability. The step wedge does not perform any of the collimation functions necessary for operation of an imaging system and thus represents yet another component to the source assembly which adds bulk, weight and expense.